Tail gas combined dust removal and purification device for ethylene glycol production

Abstract

The present application relates to the technical field of ethylene glycol production purification, and particularly relates to a tail gas combined dust removal and purification device for ethylene glycol production, which comprises a vertical cabinet, wherein a pre-washing area, a catalytic area and a fine filtering area for guiding tail gas to flow from bottom to top are arranged, and the device further comprises: a pre-washing part arranged in the pre-washing area, which comprises an air inlet pipe, a separation tool, a liquid distribution tool for containing a washing liquid, and the air inlet pipe is vertically arranged at the bottom end of the pre-washing area. In the present application, the separation tool and the liquid distribution tool are arranged, so that the cross-shaped air supply pipe spirally ascends along the air inlet pipe clockwise, the tail gas is sprayed into the pre-washing area from different axial heights and circumferential positions, and the gas-liquid mixing ring rotates counterclockwise under the driving of the worm gear, at the same time, the modified activated carbon fiber adsorption bed layer is used to physically adsorb the residual trace volatile organic compounds, and the HEPA filter layer is used for high-efficiency filtration, so that the concentration of non-methane total hydrocarbon is finally reduced to 10 mg / m 3 Below.

Description

Technical Field

[0001] This invention relates to the field of ethylene glycol production purification technology, and more particularly to a combined dust removal and purification device for tail gas in ethylene glycol production. Background Technology

[0002] The exhaust gas produced during ethylene glycol production typically contains particulate matter, carbon monoxide, methanol, acetaldehyde, and other volatile organic compounds. Direct emission of these gases would pollute the atmosphere. Currently, such exhaust gases are treated using single or simple combinations of processes, such as washing, filtration, adsorption, or catalytic oxidation.

[0003] Current technologies mostly employ a combination of spray washing and filtration to purify exhaust gases. While this can remove particulate matter and some soluble organic compounds from the exhaust gas to a certain extent, it still has shortcomings when practically applied to the purification of ethylene glycol production exhaust gases. Existing dust removal and purification equipment uses a relatively simple gas-liquid contact method, resulting in poor mixing uniformity between the exhaust gas and the scrubbing liquid within the tower. The limited contact area between the gas and liquid phases leads to low efficiency in capturing fine dust and unsatisfactory absorption of water-soluble organic compounds such as methanol and acetaldehyde. Even after pre-washing, the concentration of particulate matter and organic matter in the exhaust gas remains high, increasing the load on subsequent treatment units. Furthermore, the catalytic oxidation section in existing exhaust gas purification equipment has a fixed structure, with catalyst loading typically being integral or fixed-bed. This makes it difficult to adjust the space velocity and residence time of the treated exhaust gas through the catalyst bed according to the exhaust gas load. When the exhaust gas volume fluctuates, some gas may bypass without sufficient catalytic reaction, reducing the conversion rate of carbon monoxide and volatile organic compounds. Simultaneously, the surface of the catalytic module is prone to deactivation due to dust or carbon buildup, making maintenance and replacement difficult. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that the single method of purifying tail gas from ethylene glycol production affects air quality in the prior art, and to propose a combined dust removal and purification device for tail gas from ethylene glycol production.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A combined dust removal and purification device for tail gas in ethylene glycol production includes a vertical cabinet with a pre-washing zone, a catalytic zone, and a fine filtration zone for guiding tail gas flow from bottom to top. It also includes a pre-washing section located in the pre-washing zone, comprising an inlet pipe, a separation device, and a liquid distribution device for holding washing liquid. The inlet pipe is vertically positioned at the bottom of the pre-washing zone. The separation device includes a cross-shaped air delivery pipe fitted onto the inlet pipe, which spirals clockwise along the inlet pipe to deliver tail gas to the liquid distribution device. The liquid distribution device includes a gas-liquid mixing ring rotatably installed within the pre-washing zone. A liquid collection box is rotatably installed at the upper end of the pre-washing zone. The tail gas and washing liquid mix in the counter-clockwise rotating gas-liquid mixing ring, reducing the concentration of particulate matter in the exhaust gas to 50 mg / m³. 3 The concentrations of methanol and acetaldehyde were reduced by 80%, thus achieving the treatment of waste gas; The catalytic oxidation unit, located in the catalytic zone, includes a heating fixture and a catalytic fixture. The heating fixture includes a ventilation module, and the catalytic fixture includes a catalytic module located above the ventilation module. The waste gas is first preheated to 180-250°C by the ventilation module, and then undergoes a catalytic oxidation reaction by the catalytic module. CO is oxidized to CO2 at platinum active sites, and methanol and acetaldehyde VOCs are completely oxidized to CO2 and H2O at palladium active sites, thus obtaining purified waste gas. The adsorption and fine filtration section, located in the fine filtration zone, includes a pre-filtration layer, an activated carbon fiber adsorption bed, and a HEPA filter layer. The purified exhaust gas passes through the pre-filtration layer to intercept coarse particulate impurities, then enters the modified activated carbon fiber adsorption bed to physically adsorb residual trace VOCs. Finally, it passes through the HEPA filter layer to reduce the concentration of non-methane total hydrocarbons to 10 mg / m³. 3 The following steps yield clean gas.

[0006] Preferably, the cabinet has a first opening and a second opening that connect the pre-washing zone, the catalytic zone and the fine filtration zone in sequence, and the cabinet has maintenance windows on the side that connect the pre-washing zone and the catalytic zone respectively.

[0007] Preferably, a limiting ratchet is keyed to the intake pipe, a driven ratchet that is movably engaged with the limiting ratchet is keyed to the cross-shaped air supply pipe, and a gear post is keyed to the cross-shaped air supply pipe. A drive gear that is engaged with the gear post is rotatably installed in the cabinet, and multiple air outlets facing the catalytic module are opened in the intake pipe.

[0008] Preferably, the liquid collection box is provided with a high-pressure atomizing nozzle that connects to the gas-liquid mixing ring.

[0009] Preferably, the lower end of the gas-liquid mixing ring is connected to a collection box for collecting waste liquid after swirl.

[0010] Preferably, the ventilation module has ventilation holes, and the ventilation module has an opening rate of not less than 70%.

[0011] Preferably, the number of catalytic modules is four, and the four catalytic modules are equidistantly distributed circumferentially.

[0012] Preferably, a lifting disc is provided in the catalytic zone between four catalytic modules, and a pressurizing pad is fixedly connected to the lifting disc between each pair of adjacent catalytic modules.

[0013] Preferably, the pre-filtration layer includes four sets of circumferentially equidistant fan-shaped filter plates. When the four sets of fan-shaped filter plates are closed, they form a hollow disc structure for preliminary filtration of waste gas, and the hollow disc structure is located at the lower end of the fine filtration zone.

[0014] Preferably, the top of the cabinet has an air outlet that connects to the fine filtration zone, and the activated carbon fiber adsorption bed and the HEPA filter layer are arranged from bottom to top in the fine filtration zone through the air outlet.

[0015] Compared with the prior art, the present invention has the following advantages: 1. This invention, by setting up separation and liquid distribution fixtures, causes the cross-shaped air delivery pipe to spiral up and down clockwise along the air inlet pipe. The exhaust gas is sprayed into the pre-washing zone from different axial heights and circumferential positions. At the same time, the gas-liquid mixing ring rotates counterclockwise under the drive of the worm gear. The exhaust gas and the atomized washing liquid undergo inertial collision, interception, and dissolution absorption in the swirling field, thereby improving the gas-liquid contact area and mixing uniformity. This can effectively reduce the concentration of particulate matter, methanol, and acetaldehyde, thereby reducing the load on the subsequent catalytic oxidation and adsorption filtration units.

[0016] 2. This invention, by setting up four sets of fan-shaped modules and a lifting disc with pressurizing pads, allows the pressurizing pads to seal the strip-shaped cuts between adjacent catalytic modules when the lifting disc rises, forcing all the treated waste gas to pass through the catalytic modules, thereby improving catalyst utilization and catalytic conversion rate. When the lifting disc descends, it opens the strip-shaped cuts, increasing the airflow area, facilitating low-load operation and maintenance. At the same time, in conjunction with heating fixtures, the treated waste gas is preheated to 180-250°C, ensuring that carbon monoxide is fully oxidized into carbon dioxide and water at platinum active sites and methanol and acetaldehyde at palladium active sites, thereby improving catalytic oxidation efficiency and operational stability.

[0017] 3. This invention, by setting an adjustable pre-filtration layer in the fine filtration zone, consisting of a threaded ring, an inclined spiral cover, an elastic inclined slider, a traction connecting rod, and fan-shaped filter plates, allows the four sets of fan-shaped filter plates to form a hollow disc structure in the closed state. This allows for adjustment of the opening and closing angle according to the particulate load, controlling the effective filtration area and filtration resistance, and extending the service life of the activated carbon fiber adsorption bed and HEPA filter layer. Simultaneously, the modified activated carbon fiber adsorption bed physically adsorbs residual trace volatile organic compounds, which are then efficiently filtered by the HEPA filter layer, ultimately reducing the non-methane total hydrocarbon concentration to 10 mg / m³. 3The following steps will achieve deep purification of exhaust gases. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a combined dust removal and purification device for tail gas in ethylene glycol production proposed in this invention. Figure 2 This is a bottom view of a combined dust removal and purification device for tail gas in ethylene glycol production proposed in this invention. Figure 3 This is a front sectional view of a combined dust removal and purification device for tail gas in ethylene glycol production proposed in this invention. Figure 4 This is a side sectional view of a combined dust removal and purification device for tail gas in ethylene glycol production proposed in this invention. Figure 5 This is a schematic diagram of the pre-washing section of a combined dust removal and purification device for tail gas in ethylene glycol production, as proposed in this invention. Figure 6 This is a bottom view of the pre-washing section structure of a combined dust removal and purification device for tail gas in ethylene glycol production proposed in this invention. Figure 7 This is a cross-sectional view of the pre-washing section of a combined dust removal and purification device for tail gas in ethylene glycol production, as proposed in this invention. Figure 8 This is a schematic diagram of the catalytic oxidation section of a combined dust removal and purification device for tail gas in ethylene glycol production, as proposed in this invention. Figure 9 This is a cross-sectional view of the catalytic oxidation section of a combined dust removal and purification device for tail gas in ethylene glycol production, as proposed in this invention. Figure 10 This is a cross-sectional view of the adsorption and fine filtration section of a combined dust removal and purification device for tail gas in ethylene glycol production proposed in this invention.

[0019] In the diagram: 1. Vertical cabinet; 11. Pre-washing area; 12. Catalytic zone; 13. Fine filtration zone; 2. Pre-washing section; 21. Air inlet pipe; 22. Separation fixture; 221. Limiting ratchet; 222. Cross-shaped air delivery pipe; 223. Driven ratchet; 224. Gear post; 225. Drive gear; 226. Air outlet; 23. Liquid distribution fixture; 231. Worm gear; 232. Driven worm gear; 233. Gas-liquid mixing ring; 234. Liquid collection box; 235. High-pressure atomizing nozzle; 24. Recycle collection box; 3. Catalytic oxidation section; 31. Heating fixture; 311. Ventilation module; 312. Electric heater; 313. Ventilation hole; 32. Catalytic fixture; 321. Fan-shaped module; 322. Catalytic module; 323. Lifting disc; 324. Pressure-boosting pad; 4. Adsorption and fine filtration section; 41. Pre-filter layer; 411. Threaded ring; 412. Inclined spiral cover; 413. Elastic inclined slider; 414. Fan-shaped filter plate; 415. Traction link; 42. Activated carbon fiber adsorption bed; 43. HEPA filter layer. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] Reference Figures 1-10 A combined dust removal and purification device for ethylene glycol production tail gas is disclosed, used for continuous combined purification of tail gas containing dust, carbon monoxide, methanol, acetaldehyde, and other volatile organic compounds generated during ethylene glycol production. It includes a vertical tower-type cabinet 1, employing a vertical cylindrical or rectangular box structure, preferably made of Q345R low-alloy high-strength steel plate welded together, with a wall thickness of 6-12mm. The inner wall is entirely coated with a composite anti-corrosion coating system of epoxy zinc-rich primer and polyurethane topcoat. The bottom is equipped with a skirt or saddle-type support, fixed to a concrete foundation by anchor bolts. The foundation embedded parts are cast in one go during the civil construction phase.

[0022] The vertical cabinet 1 has a pre-washing zone 11, a catalytic zone 12, and a fine filtration zone 13 that guide the exhaust gas to flow from bottom to top. Inside the vertical cabinet 1, there are a first opening and a second opening that sequentially connect the pre-washing zone 11, the catalytic zone 12, and the fine filtration zone 13. Both the first and second openings can be equipped with flow equalization plates, guide cones, or gas collecting discs to reduce airflow deviation and ensure a uniform transition of the treated exhaust gas between the zones.

[0023] To further explain, the guide cone adopts a conical or parabolic structure with a cone angle of 30°-60°, and is fixed at the center of the inlet to evenly disperse the high-speed airflow from the center to the outer periphery. The gas collecting plate has an inverted conical or umbrella-shaped structure with an annular liquid collecting groove on the edge, which has the dual functions of uniform airflow distribution and condensate collection.

[0024] The side wall of the cabinet 1 has an inspection window, which corresponds to the pre-washing area 11 and the catalytic area 12 respectively, to facilitate the disassembly, cleaning and replacement of internal components. The inspection window adopts a flange-sealed quick-opening door structure. The door panel material is the same as the cabinet 1 body. The sealing surface is sealed with a high-temperature resistant silicone rubber O-ring or a spiral wound metal gasket. High-strength bolts are distributed, and anti-loosening washers and anti-loosening nuts are provided.

[0025] Reference Figures 1-4 The device also includes a pre-washing section 2, a catalytic oxidation section 3, and an adsorption and fine filtration section 4. Reference Figure 3 The pre-washing section 2 is located in the pre-washing zone 11 and is used to humidify, remove dust, and initially remove water-soluble organic matter from the high-temperature exhaust gas. It includes an air inlet pipe 21, a separation fixture 22, a liquid distribution fixture 23 for holding the washing liquid, and a collection box 24. The intake pipe 21 is vertically installed at the bottom of the pre-washing area 11. The lower end of the intake pipe 21 is connected to the exhaust gas inlet pipe via a flange. The flange sealing surface is either a raised face or a tongue and groove face, and the gasket is a flexible graphite composite gasket or a polytetrafluoroethylene-coated gasket. A manual butterfly valve or a pneumatic butterfly valve can also be installed at the lower end of the intake pipe 21 for shutting off the gas supply during maintenance.

[0026] Reference Figure 5 The separation fixture 22 is used to release the exhaust gas entering the pre-wash zone 11 according to the preset rotation direction and spiral lifting path. It is preferably circumferentially positioned by a flat key or spline connection, and axially positioned by a shoulder or retaining ring, so as to form gas-liquid contact at different heights.

[0027] The separation fixture 22 includes a limiting ratchet 221 keyed to the air inlet pipe 21. The limiting ratchet 221 is a fixed one-way ratchet. A cross-shaped air supply pipe 222, which is movably installed in the cabinet 1, is mounted on the air inlet pipe 21. A driven ratchet 223, which is movably engaged with the limiting ratchet 221, is keyed to the cross-shaped air supply pipe 222. A one-way pawl is provided on the driven ratchet 223. The one-way pawl adopts a spring-loaded structure. The spring is preferably a stainless steel compression spring. One end of the spring is fixed to the pawl body, and the other end is fixed to the hub of the cross-shaped air supply pipe 222, ensuring that the pawl always maintains contact with the ratchet tooth surface. When the cross-shaped air supply pipe 222 rotates forward under the drive gear 225, the pawl slides along the ratchet tooth surface, and the cross-shaped air supply pipe 222 rotates freely. When the drive gear 225 rotates in the reverse direction, the pawl engages with the ratchet tooth groove, and the cross-shaped air supply pipe 222 is locked. At this time, axial lifting and lowering are achieved only by the helical guide structure without rotation.

[0028] Specifically, the cross-shaped air delivery pipe 222 has a central sleeve and multiple air delivery arms extending outward from the central sleeve, with airflow channels formed inside the air delivery arms. A spiral guide structure is provided between the inner wall of the central sleeve of the cross-shaped air delivery pipe 222 and the outer wall of the air inlet pipe 21. Preferably, a multi-head spiral groove is formed on the outer wall of the air inlet pipe 21. The lead angle of the spiral groove is preferably 15°-30°, and the lead is 80-200mm / turn, that is, the cross-shaped air delivery pipe 222 rises or falls 80-200mm axially for each rotation. Guide balls or sliders are embedded in the inner wall of the cross-shaped air delivery pipe 222, enabling the cross-shaped air delivery pipe 222 to perform spiral lifting and lowering motion relative to the air inlet pipe 21. When a slider is used instead of balls, the slider material is preferably self-lubricating engineering plastic, and the slider cross-section is rectangular or T-shaped, forming a sliding guide pair with the spiral groove.

[0029] A gear column 224 is keyed to the cross-shaped air supply pipe 222. A drive gear 225, meshing with the gear column 224, is rotatably mounted in the cabinet 1. The rotational power of the drive gear 225 can be provided by a geared motor, servo motor, or stepper motor. The motor is mounted on a mounting bracket on the outer wall of the cabinet 1. The output shaft is connected to the rotating shaft of the drive gear 225 via a coupling. A mechanical seal or magnetohydrodynamic seal is provided at the coupling to prevent exhaust gas leakage. The drive gear 225 drives the cross-shaped air supply pipe 222 to rotate around the intake pipe 21 via the gear column 224. When the cross-shaped air supply pipe 222 rotates, the driven ratchet 223 slides or engages along the ratchet tooth surface of the limiting ratchet 221. At the same time, the helical guide structure converts the rotational motion into axial lifting motion, causing the cross-shaped air supply pipe 222 to spirally lift and lower along the intake pipe 21 in a clockwise direction.

[0030] It should be noted that the output shaft of the drive motor is connected to the outer magnetic ring, and an isolation sleeve is installed inside the wall of the cabinet 1. An inner magnetic ring is fixedly installed at the bottom of the central sleeve of the cross-shaped air supply pipe 222. The inner magnetic ring and the outer magnetic ring are coaxially fitted and positioned relative to the isolation sleeve. When the drive motor drives the outer magnetic ring to rotate, it drives the inner magnetic ring to rotate through magnetic coupling, thereby driving the cross-shaped air supply pipe 222 to rotate around the air inlet pipe 21. Under the action of the spiral guide structure, the cross-shaped air supply pipe 222 spirals up and down in a clockwise direction along the air inlet pipe 21. This drive method eliminates the need to open a dynamic sealing hole for the rotating shaft on the cabinet 1, which can effectively improve the sealing performance of the pre-wash zone 11 and prevent the washing liquid in the pre-wash zone 11 from leaking through the dynamic seal along the rotating shaft.

[0031] Multiple air outlets 226 are provided in the air inlet pipe 21, facing the liquid distribution fixture 23. The air outlets 226 are arranged at intervals along the axial and circumferential directions of the air inlet pipe 21, and all face the area where the liquid distribution fixture 23 is located. The diameter of the air outlets 226 is 5-20 mm, the axial spacing along the air inlet pipe 21 is 50-150 mm, and 4-8 are evenly distributed circumferentially. Adjustable flow valves or fixed nozzles can be installed at the orifices of the air outlets 226 to adjust the flow distribution of each layer of air outlets 226. The preferred spray direction of the air outlets 226 is at an oblique angle of 30°-60° to the axis of the air inlet pipe 21, so that the exhaust gas forms a swirling or spiral jet after being ejected, enhancing the turbulent mixing effect with the washing liquid.

[0032] In another embodiment, a rotatable throttling sleeve is provided inside the air outlet 226. The throttling sleeve has through holes of different diameters. By rotating the throttling sleeve, the effective flow area of ​​the air outlet 226 is changed, thereby adjusting the distribution ratio of air volume of each layer to adapt to different working conditions.

[0033] The cross-shaped air supply pipe 222 spirals up and down clockwise along the air inlet pipe 21 to deliver exhaust gas to the liquid distribution fixture 23. Preferably, the air outlet 226 is an oblique or tangential spray hole to create a swirling or impinging flow when the exhaust gas is ejected, enhancing the contact effect with the washing liquid. A sealing end cap or plug can be installed at the upper end of the air inlet pipe 21 to prevent the exhaust gas from directly short-circuiting out from the top. During the spiraling up and down process, the cross-shaped air supply pipe 222 delivers the exhaust gas into the liquid distribution fixture 23 from different axial heights and different circumferential positions, improving the spatial uniformity of the gas and liquid phases in the pre-washing zone 11.

[0034] To further explain, when the cross-shaped air delivery pipe 222 rotates, the air outlets of each air delivery arm sweep across the air outlets on the air inlet pipe in sequence, realizing pulsed intermittent air delivery and enhancing the disturbance effect of gas-liquid mixing.

[0035] To prevent dynamic seal leakage of washing liquid along the rotating shaft in the pre-wash zone 11, in another embodiment, the driving method of the separation fixture 22 is improved to magnetic coupling drive. Specifically, a drive motor is fixedly installed on the outer wall of the cabinet 1, and the output shaft of the drive motor is connected to an outer magnetic ring. An isolation sleeve is provided inside the wall of the cabinet 1. An inner magnetic ring is fixedly installed at the bottom of the central sleeve of the cross-shaped air supply pipe 222. The inner magnetic ring and the outer magnetic ring are coaxially fitted and positioned relative to the isolation sleeve. When the drive motor drives the outer magnetic ring to rotate, the inner magnetic ring is driven to rotate through magnetic coupling, thereby driving the cross-shaped air supply pipe 222 to rotate around the air inlet pipe 21. Under the action of the spiral guide structure, the cross-shaped air supply pipe 222 spirals up and down in a clockwise direction along the air inlet pipe 21. This driving method eliminates the need to open a dynamic seal hole for the rotating shaft on the cabinet 1, which can effectively improve the sealing performance of the pre-wash zone 11.

[0036] To further explain, the drive motor is preferably a servo motor with a continuously adjustable speed from 0 to 150 r / min. By adjusting the speed of the drive motor, the spiral lifting speed of the cross-shaped air delivery pipe 222 can be controlled, thereby controlling the axial release range of the exhaust gas within the pre-wash zone 11. A one-way return spring can be added between the limiting ratchet 221 and the driven ratchet 223 to ensure that the cross-shaped air delivery pipe 222 maintains circumferential air delivery uniformity during its descent.

[0037] Reference Figure 6 The liquid distribution fixture 23 is used to hold and atomize the washing liquid, so that the washing liquid and the exhaust gas will have countercurrent and tangential contact in the pre-washing zone 11. It includes a worm gear 231 rotatably installed outside the cabinet 1. The worm of the worm gear 231 can be driven by a motor. A driven worm gear 232 that meshes with the worm gear 231 is rotatably installed on the cabinet 1. A gas-liquid mixing ring 233 that is rotatably installed in the pre-washing zone 11 is fixedly installed on the driven worm gear 232. The gas-liquid mixing ring 233 can be set as a hollow annular structure. It is provided with swirling blades, baffles or impact baffles inside to enhance gas-liquid mixing. Furthermore, by adding detachable swirling blades inside the gas-liquid mixing ring 233, the installation angle of the swirling blades is 20°-45° and the installation angle of the swirling blades can be adjusted according to the exhaust gas volume. When the exhaust gas enters the gas-liquid mixing ring 233 tangentially, the swirl blades force the airflow to generate a strong rotational motion, forming a centrifugal force field, which causes the washing liquid droplets to diffuse towards the outer wall surface under the action of centrifugal force, increasing the gas-liquid contact area.

[0038] Furthermore, the swirl vane is hinged to the inner wall of the gas-liquid mixing ring 233 via a pin, and the tail end of the swirl vane is connected to an adjusting rod. The adjusting rod extends to the outside of the gas-liquid mixing ring 233 and is driven by a handwheel or an electric actuator.

[0039] A liquid collection box 234 is rotatably installed at the upper end of the pre-wash zone 11 to hold the washing liquid. It is connected to an external washing liquid supply line via a rotary joint. A supply pump delivers the washing liquid into the collection box 234. The supply pump is a corrosion-resistant centrifugal pump or a diaphragm pump, and the flow rate is determined based on the liquid-to-gas ratio and the number of nozzles. The washing liquid pressure can be 0.3-0.8 MPa. A high-pressure atomizing nozzle 235, connected to a gas-liquid mixing ring 233, is provided on the collection box 234. The high-pressure atomizing nozzle 235 can be a spiral nozzle, a fan-shaped nozzle, or a centrifugal atomizing nozzle, and the preferably diameter of the sprayed washing liquid droplets is 20-200 μm.

[0040] To further improve the atomization effect, another embodiment preferably uses a dual-fluid atomizing nozzle. The liquid inlet of the dual-fluid atomizing nozzle is connected to the liquid collection box 234, and the gas inlet is connected to the compressed air source through the atomizing medium pipeline. The compressed air pressure is 0.3-0.5 MPa, the washing liquid pressure is 0.2-0.4 MPa, the liquid-to-gas ratio is controlled between 0.3 and 1.0, and the average diameter of the droplets at the outlet of the dual-fluid atomizing nozzle is controlled between 30-100 μm.

[0041] The exhaust gas and scrubbing liquid are mixed in a counterclockwise rotating gas-liquid mixing ring 233 to reduce the particulate matter concentration to 50 mg / m³. 3 Specifically, particulate matter is captured through inertial collision, interception and coagulation, while water-soluble organic matter such as methanol and acetaldehyde partially dissolves in the washing liquid, reducing the concentration of methanol and acetaldehyde by 80%, thus obtaining treated waste gas.

[0042] The collection box 24 is used to collect the used washing liquid. The collection box 24 can be equipped with a conical collection hopper, a liquid level observation window, a drain valve, and a sludge drain valve. The washing liquid can be recycled after sedimentation and filtration, or it can be periodically discharged for treatment. The liquid level observation window is a tempered glass tube level gauge or a magnetic float level gauge, with a range covering more than 80% of the effective height of the collection hopper. A DN25 sludge drain port is also provided at the bottom of the collection hopper for discharging settled heavy metal dust and sludge.

[0043] Reference Figure 8 and Figure 9 The catalytic oxidation unit 3 is located in the catalytic zone 12 and is used to preheat and catalytically oxidize the pre-washed waste gas, converting carbon monoxide and residual organic matter into carbon dioxide and water. It includes a heating fixture 31 and a catalytic fixture 32. The heating fixture 31 includes a ventilation module 311, which is located above the first inlet. The ventilation module 311 can be made of honeycomb ceramic heat storage body, metal perforated plate or foam metal material.

[0044] An electric heater 312 is fixedly installed on the ventilation module 311. The electric heater 312 can be a PTC heating element, a heating wire, or a far-infrared heating tube, and the heating temperature is controlled by a temperature controller and a temperature sensor. The ventilation module 311 has ventilation holes 313, and the opening ratio of the ventilation module 311 is not less than 70% to ensure low pressure loss and good airflow distribution.

[0045] In some implementations, the temperature sensor is a type K or type N thermocouple, installed on the outlet side of the ventilation module 311, with a temperature measurement range of 0-500℃ and an accuracy of ±1.5℃. The temperature controller is a PID self-tuning intelligent temperature controller, which outputs a 4-20mA signal to control a solid-state relay or a thyristor power regulator to achieve stepless adjustment of the power of the electric heater 312.

[0046] The catalytic fixture 32 includes a fan-shaped module 321 fixedly mounted on the inner wall of the catalytic zone 12. This fan-shaped module 321 is a 1 / 4 or 1 / 6 arc-shaped support frame, which can be made of heat-resistant stainless steel or ceramic fiber reinforced composite material, and is used to support the catalytic module 322. A ceramic fiber sealing rope is installed between the fan-shaped module 321 and the inner wall of the catalytic zone 12 to prevent bypass leakage of treated waste gas from the gap between the fan-shaped module 321 and the inner wall of the catalytic zone 12.

[0047] A catalytic module 322 is disposed on the fan-shaped module 321 above the ventilation module 311. The catalytic module 322 is preferably an integral honeycomb ceramic catalyst, with a γ-alumina and cerium-zirconium composite oxide coating on the support surface and loaded with platinum and palladium noble metal active components. Among them, the platinum active sites are used for the oxidation of carbon monoxide to carbon dioxide, and the palladium active sites are used for the complete oxidation of volatile organic compounds such as methanol and acetaldehyde to carbon dioxide and water.

[0048] It should be noted that there are four sets of both the fan-shaped modules 321 and the catalytic modules 322, which are circumferentially equidistantly distributed in a one-to-one correspondence. There is a strip-shaped cut between each pair of adjacent fan-shaped modules 321. The opening of the strip-shaped cut increases the airflow area, which facilitates the system's pressure reduction start-up, low-load operation, or maintenance. A lifting disc 323 is set in the catalytic zone 12, located between the four sets of catalytic modules 322. The lifting drive of the lifting disc 323 can be an electric push rod, a cylinder, a hydraulic cylinder, a ball screw and nut mechanism, or a gear and rack mechanism.

[0049] The lifting disc 323 is fixedly connected to a pressure-boosting pad 324 located in the strip-shaped cut between each pair of adjacent catalytic modules 322. The pressure-boosting pad 324 is made of high-temperature resistant elastic material, such as fluororubber or silicone rubber, or has a stainless steel corrugated skeleton embedded inside it to improve the heat fatigue resistance and deformation resistance of the pressure-boosting pad 324.

[0050] When the lifting disc 323 rises, the pressurizing pad 324 is embedded in the strip-shaped cut between each pair of adjacent fan-shaped modules and closes the bypass channel, forcing all the treated waste gas to pass through the catalytic module 322, thereby improving the catalytic conversion rate. When the lifting disc 323 falls, the strip-shaped cut opens, increasing the airflow area, which facilitates the system's pressure reduction start-up, low-load operation, or maintenance.

[0051] The waste gas is first preheated to 180-250°C by the ventilation module 311, and then undergoes catalytic oxidation reaction by the catalytic module 322. CO is oxidized to CO2 at the platinum active sites, and volatile organic compounds such as methanol and acetaldehyde are completely oxidized to carbon dioxide and water at the palladium active sites, thus obtaining purified waste gas.

[0052] As operating time increases, the activity of the catalytic module 322 may decrease due to carbon buildup, sulfide deposits, or trace dust accumulation. To extend the service life of the catalytic module 322, a regeneration bypass is added in another embodiment. The regeneration bypass includes a regeneration inlet pipe and a regeneration outlet pipe. The regeneration inlet pipe is connected to the lower end of the catalytic zone 12, and the regeneration outlet pipe is connected to the upper end of the catalytic zone 12. A regeneration heater and a regeneration fan are installed on the regeneration inlet pipe. The regeneration heater heats the regeneration gas to 300-400°C.

[0053] When the pressure difference of catalytic module 322 increases or the catalytic conversion rate decreases, the inlet and outlet valves of the treated waste gas are closed, the regeneration bypass is opened, and hot air or regeneration gas containing a low concentration of oxygen is introduced to regenerate catalytic module 322 in situ, so as to restore the catalytic activity of platinum and palladium active sites. The desorption gas generated during the regeneration process can be discharged through the regeneration exhaust pipe and enter the tail gas purification device.

[0054] Furthermore, the lifting drive method of the lifting disc 323 is improved to a servo electric cylinder drive. The servo electric cylinder is fixed outside the cabinet 1, and its push rod extends into the catalytic zone 12 through a bellows seal and is fixedly connected to the lifting disc 323. The servo electric cylinder, together with the displacement sensor, can precisely control the axial displacement of the lifting disc 323, so that the compression of the pressure pad 324 can be precisely controlled, ensuring that the pressure pad 324 can reliably embed into the strip-shaped cut and seal the bypass channel.

[0055] Reference Figure 10 The adsorption and fine filtration section 4 is located in the fine filtration zone 13 and is used to further remove coarse particulate impurities, residual trace volatile organic compounds and fine particulate matter from the purified exhaust gas. It includes a pre-filtration layer 41, an activated carbon fiber adsorption bed 42 and a HEPA filter layer 43. The purified exhaust gas passes through a pre-filter layer 41 to intercept coarse particulate impurities. This layer intercepts coarse particulate impurities, catalyst powder, or detached solid particles that may be carried in the purified exhaust gas. It includes a threaded ring 411 located at the upper end of the vertical cabinet 1, which is situated at the lower end of the fine filtration zone 13. A sloping spiral cover 412 is fitted onto the threaded ring 411. The rotation of the sloping spiral cover 412 can be driven by a motor, a worm gear 231, or a manually adjustable handwheel. Specifically, a geared ring can be provided on the outer edge of the sloping spiral cover 412. A geared motor is installed on the outer wall of the vertical cabinet 1, and the output shaft of the geared motor meshes with the geared ring via a drive gear, thereby driving the sloping spiral cover 412 to rotate. Furthermore, an elastic inclined slider 413 extending into the fine filtration zone 13 is provided in the vertical cabinet 1. The elastic inclined slider 413 moves against the sloping spiral cover 412. When the sloping spiral cover 412 rotates, it moves axially along the threaded ring 411, and its inclined end pushes the elastic inclined slider 413 to undergo radial or axial displacement.

[0056] A traction rod 415 is connected to the upper pin of the elastic inclined slider 413. A fan-shaped filter plate 414 is slidably installed in the cabinet 1, which is rotatably connected to the elastic inclined slider 413 and extends into the fine filtration zone 13. There are four sets of fan-shaped filter plates 414, which are equidistantly distributed in the circumference. The four sets of fan-shaped filter plates 414 form a hollow disc structure for preliminary filtration of waste gas when closed. The hollow disc structure is located at the lower end of the fine filtration zone 13. The four sets of fan-shaped filter plates 414 form a hollow disc structure at the lower end of the fine filtration zone 13 when closed, which is used for preliminary filtration and purification of waste gas.

[0057] When the inclined spiral cover 412 rotates, the elastic inclined slider 413 drives the sector filter plates 414 to move via the traction connecting rod 415, causing the four sets of sector filter plates 414 to switch between closed and open states. By adjusting the opening and closing angle of the sector filter plates 414, the effective filtration area and interception accuracy of the pre-filtration layer 41 can be adjusted, thereby adapting to different particulate loads and extending the service life of subsequent filtration units.

[0058] The remaining trace VOCs are then physically adsorbed into the modified activated carbon fiber adsorption bed 42. The modified activated carbon fiber adsorption bed 42 is used to physically adsorb the remaining trace volatile organic compounds. It can be made of modified activated carbon fiber felt or folded activated carbon fiber modules, and the specific surface area of ​​the activated carbon fiber is preferably greater than 1200 m². 2 / g, and can be modified by acid washing, alkali washing or loading with transition metal oxides to improve the adsorption capacity and selectivity for polar organic compounds such as methanol and acetaldehyde. The activated carbon fiber adsorption bed 42 can be configured as a multi-layer corrugated structure, with support mesh and sealing gaskets between layers to prevent airflow short-circuiting and reduce bed pressure drop.

[0059] In another embodiment, the modified activated carbon fiber adsorption bed 42 is composed of multiple activated carbon fiber modules. Each activated carbon fiber module is installed in a drawer-type frame. The drawer-type frame slides with the guide rail on the side wall of the fine filtration zone 13 and can be pulled out and replaced through the replacement port on the side wall of the fine filtration zone 13, which can avoid removing the activated carbon fiber adsorption bed 42 as a whole from the air outlet after shutdown.

[0060] Finally, the concentration of non-methane total hydrocarbons was reduced to 10 mg / m³ using HEPA filter layer 43. 3 The HEPA filter layer 43 can be made of folded ultrafine glass fiber filter paper or polypropylene meltblown filter paper for efficient filtration of fine particulate matter to obtain clean gas.

[0061] An aerosol generation port is located below the HEPA filter layer 43, and a scanning sampling port is located above it for in-situ leak detection of the HEPA filter layer 43. By injecting aerosol and sampling upstream and downstream respectively, it can be determined whether there is local damage or poor sealing of the HEPA filter layer 43.

[0062] To avoid excessively high filtration resistance or decreased filtration efficiency, a differential pressure detection module is added in another embodiment, including a first pressure tap and a second pressure tap. The first pressure tap is located upstream of the pre-filtration layer 41, and the second pressure tap is located downstream of the pre-filtration layer 41. The first and second pressure taps are respectively connected to a differential pressure transmitter. The differential pressure transmitter output signal is connected to a controller, and the controller is interlocked with the drive motor of the inclined spiral cover 412.

[0063] When the differential pressure transmitter detects a differential pressure value exceeding the set upper limit, the controller controls the drive motor to drive the inclined spiral cover 412 to rotate, causing the elastic inclined slider 413 to drive the sector filter plate 414 to increase the opening and closing angle through the traction link 415, thereby increasing the effective filtration area, reducing the filtration velocity, and thus controlling the filtration resistance. When the differential pressure value is lower than the set lower limit, the opening and closing angle of the sector filter plate 414 is reduced to restore the initial filtration accuracy and interception efficiency.

[0064] An air outlet is provided at the top of the cabinet 1, which is connected to the fine filtration zone 13. The activated carbon fiber adsorption bed 42 and the HEPA filter layer 43 are arranged from bottom to top in the fine filtration zone 13 through the air outlet, and the clean gas is discharged through the air outlet.

[0065] It should be noted that the specific model and specifications of the electric heater 312 need to be selected and determined according to the actual specifications of the device. The specific selection calculation method adopts the existing technology in this field, so it will not be elaborated here.

[0066] The functional principle of this invention can be explained through the following operational methods: After the induced draft fan is started, the ethylene glycol production tail gas enters the pre-washing zone 11 through the air inlet pipe 21; Driven by a geared motor, the drive gear 225 rotates and drives the cross-shaped air supply pipe 222 to rotate through the gear column 224. The cross-shaped air supply pipe 222 spirals up and down along the air inlet pipe 21 under the cooperation of the limiting ratchet 221, the driven ratchet 223 and the spiral guide structure, so that the exhaust gas is sprayed into the pre-washing zone 11 from the air outlet 226 at different heights and different circumferential positions. Driven by a motor, the worm gear 231 rotates the driven worm wheel 232, which in turn rotates the gas-liquid mixing ring 233 counterclockwise. The high-pressure atomizing nozzle 235 in the liquid collection box 234 sprays atomized washing liquid into the gas-liquid mixing ring 233. The exhaust gas and washing liquid undergo inertial collisions, droplet capture, and dissolution absorption in the swirling flow field. Particulate matter is washed into the return collection box 24, reducing the concentrations of methanol and acetaldehyde, thus obtaining treated exhaust gas.

[0067] The treated waste gas enters the catalytic zone 12 through the first inlet, first passing through the ventilation module 311, and is preheated to 180-250℃ by the electric heater 312. The lifting disc 323 rises, and the pressurizing pad 324 seals the strip-shaped cut, allowing all the treated waste gas to pass through the four sets of catalytic modules 322. Under the action of platinum and palladium active sites, carbon monoxide, methanol, and acetaldehyde are oxidized into carbon dioxide and water, resulting in purified waste gas. The purified exhaust gas enters the fine filtration zone 13 through the second inlet. First, the hollow disc structure composed of fan-shaped filter plates 414 in the pre-filtration layer 41 intercepts coarse particulate impurities. Then, it enters the modified activated carbon fiber adsorption bed 42 to adsorb residual trace volatile organic compounds. Finally, after high-efficiency filtration by the HEPA filter layer 43, the concentration of non-methane total hydrocarbons is reduced to below 10 mg / m3, and clean gas is obtained and discharged from the outlet.

[0068] When maintenance is required, the components in the pre-washing section 2 and the catalytic oxidation section 3 can be cleaned, repaired or replaced through the maintenance window; the replacement of the catalytic module 322, the cleaning of the cross-shaped gas delivery pipe 222, the gas-liquid mixing ring 233 and the cleaning of the return collection box 24 can all be completed by opening the maintenance window after the machine is stopped.

[0069] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A combined dust removal and purification device for tail gas in ethylene glycol production, comprising a vertical cabinet (1), wherein a pre-washing zone (11), a catalytic zone (12), and a fine filtration zone (13) are provided to guide the tail gas to flow from bottom to top, characterized in that, Also includes: The pre-washing section (2), located in the pre-washing zone (11), includes an air inlet pipe (21), a separation device (22), and a liquid distribution device (23) for holding washing liquid. The air inlet pipe (21) is vertically positioned at the bottom of the pre-washing zone (11). The separation device (22) includes a cross-shaped air delivery pipe (222) spirally surrounding the outer wall of the air inlet pipe (21). The cross-shaped air delivery pipe (222) spirals up and down clockwise along the air inlet pipe (21) to deliver exhaust gas to the liquid distribution device (23). The liquid distribution device (23) includes a gas-liquid mixing ring (233) rotatably installed in the pre-washing zone (11). A liquid collection box (234) is rotatably installed in the upper part of the pre-washing zone (11). The gas-liquid mass transfer is enhanced through bidirectional swirling shearing action, reducing the particulate matter concentration in the exhaust gas to 50 mg / m³. 3 The concentrations of methanol and acetaldehyde were reduced by 80%, thus achieving the treatment of waste gas. The catalytic oxidation unit (3) is located in the catalytic zone (12) and includes a heating fixture (31) and a catalytic fixture (32). The heating fixture (31) includes a ventilation module (311), and the catalytic fixture (32) is provided with a catalytic module (322) loaded with platinum / palladium bimetallic active components, so that CO is oxidized at low temperature at platinum sites and methanol and acetaldehyde are deeply mineralized into CO2 and H2O at palladium sites. The adsorption and fine filtration section (4), located in the fine filtration zone (13), includes a pre-filtration layer (41), an activated carbon fiber adsorption bed (42), and a HEPA filter layer (43), which physically adsorbs and intercepts residual trace VOCs, reducing the concentration of non-methane total hydrocarbons to 10 mg / m³. 3 The following steps yield clean gas.

2. The combined dust removal and purification device for tail gas in ethylene glycol production according to claim 1, characterized in that, The cabinet (1) has a first port and a second port that are sequentially connected to the pre-washing zone (11), the catalytic zone (12) and the fine filtration zone (13), and the cabinet (1) has maintenance windows on its side that are respectively connected to the pre-washing zone (11) and the catalytic zone (12).

3. The combined dust removal and purification device for tail gas in ethylene glycol production according to claim 2, characterized in that, The intake pipe (21) is keyed to a limiting ratchet (221), the cross-shaped air supply pipe (222) is keyed to a driven ratchet (223) that is movably engaged with the limiting ratchet (221), and the cross-shaped air supply pipe (222) is keyed to a gear column (224). The cabinet (1) is rotatably installed with a drive gear (225) that is engaged with the gear column (224). The intake pipe (21) has multiple air outlets (226) facing the catalyst module (322).

4. The combined dust removal and purification device for tail gas in ethylene glycol production according to claim 3, characterized in that, The liquid collection box (234) is provided with a high-pressure atomizing nozzle (235) that connects to the gas-liquid mixing ring (233).

5. The combined dust removal and purification device for tail gas in ethylene glycol production according to claim 4, characterized in that, The lower end of the gas-liquid mixing ring (233) is connected to a collection box (24) for collecting waste liquid after swirling.

6. The combined dust removal and purification device for tail gas in ethylene glycol production according to claim 5, characterized in that, The ventilation module (311) is provided with ventilation holes (313), and the opening ratio of the ventilation module (311) is not less than 70%.

7. The combined dust removal and purification device for tail gas in ethylene glycol production according to claim 6, characterized in that, The number of catalyst modules (322) is four, and the four catalyst modules (322) are equidistantly distributed in the circumferential direction.

8. The combined dust removal and purification device for tail gas in ethylene glycol production according to claim 7, characterized in that, The catalytic zone (12) is provided with a lifting disc (323) located between four catalytic modules (322), and a pressure pad (324) located between each two adjacent catalytic modules (322) is fixedly connected to the lifting disc (323).

9. The combined dust removal and purification device for tail gas in ethylene glycol production according to claim 8, characterized in that, The pre-filtration layer (41) includes four sets of circumferentially spaced fan-shaped filter plates (414), which are closed and spliced ​​together to form a hollow disc structure at the bottom of the fine filtration zone (13).

10. A combined dust removal and purification device for tail gas in ethylene glycol production according to claim 9, characterized in that, The top of the cabinet (1) has an air outlet that connects to the fine filtration zone (13), and the activated carbon fiber adsorption bed (42) and the HEPA filter layer (43) are arranged from bottom to top in the fine filtration zone (13) through the air outlet.

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